This invention is an improvement on the structure of U.S. Pat. No. 2,983,216 which is incorporated herein by reference.
Rain caps constructed in accordance with the invention were made with the sheet metal halves of the balance arm body pierced and engaged onto a bushing, usually by force fit. Welding was feasible but the engagement was edgewise. It was found that these pivotal arrangements wore out because of the continuous beating that was administered during use. The joint between the pierced holes and the bushing loosened and rendered the device ineffectual. The other parts of the device would also wear out quickly because of this. Especially this was true for large devices, as for example where the exhaust pipe or stack had a diameter of more than five inches. It can be appreciated that these devices were heavy and the inertia of large moving pieces exerted considerable shock on the bearing structure.
The invention herein is intended to solve the problem, but does so in a manner which is applicable to small sizes of rain cap as well as large.